I had a minor ick outbreak... then a pretty substantial outbreak... then a total catastrophic fish loss. Now the tank only has one chromis' in it and after posting this I'll move him to QT. (I hate learning things the hard way )

My question is: How long should I leave the DT empty? I've researched lengths of time but everyone seems to have a different answer. Also, is it OK to keep the hermits/snails in there during the empty period?